Invisible Cloak Made of Metamaterial

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Invisible Cloak Made of Metamaterial

• B96901128 ???

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Outline

• 1. Basic Concepts
• 2. Free-Space Cloak in 2006
• 3. Carpet Cloak in 2008
• 4. Carpet Cloak in 2009
• 5. Conclusions
• 6. References

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Basic Concepts

• Transformation optics and quasiconformal mapping.
• Inhomogeneous materialcurved space, apply
  Fermats principle.
• Cloaking, concentrating, rotating, bending, black
  hole,..

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Equivalence of two space
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Free-Space Cloak in 2006

• First proposed by Pendry1 and
  Leonhardt2.theorem in book3-4

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Free-Space Cloak in 2006
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Free-Space Cloak in 2006

• Used reduced parameter to realized in microwave
  frequency5.

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Free-Space Cloak in 2006

• Drawback
• 1. Singular parameter
• 2. Need to use resonant structure,
• narrow bandwidth and high loss.
• 3. Anisotropic
• Hard to fabricate and applied.

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Carpet Cloak in 2008

• Instead crushed cloaked object to a point, we can
  also crushed to a line or a sheet(carpet cloak).
• Broad-band, low loss and isotropic, easy to
  fabricate.
• Hide the tank or the aircraft on the ground.

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Carpet Cloak in 2008

• Proposed by Pendry6

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Carpet Cloak in 2008

• The optimal map is generated by minimizing the
  Modified-Liao functional upon slipping BC3.
• Choose smallest anisotropy factor(1.042).

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Carpet Cloak in 2008

• Realized in microwave frequency7 and optic
  frequency8-9.

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Carpet Cloak in 2008
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Carpet Cloak in 2008

• Drawback
• 1.Carpet cloak has very large size (height
  ratio65.7)
• 2.Background is not free space.
• Therefore, T.J.Cui proposed a compact-sized
  broadband carpet cloak10.

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Carpet Cloak in 2009

• Set background to free space, and use n1 to
  replace the region where nlt1.
• Height ratio from 65.7 to 7.33.

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Carpet Cloak in 2009
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Carpet Cloak in 2009

• Different h, different e.

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Carpet Cloak in 2009

• Measure at different frequency.

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Carpet Cloak in 2009

• Compare full-parameter carpet cloak and
  simplified carpet cloak(simulation).

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Directive Free-Space Cloak
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Directive Free-Space Cloak

• Simulate and measure at different frequency.

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Directive Free-Space Cloak
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Conclusions

• Compact-sized, broadband carpet cloak is
  developed, and it represents a major step towards
  real applications of invisibility devices.

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Reference

• 1 J. B. Pendry, D. Schurig, and D. R. Smith,
  Controlling electromagnetic fields, Science
  312, 1780-1782 (2006).
• 2 U. Leonhardt, Optical conformal mapping,
  Science 312, 1777-1780 (2006).
• 3 P. Knupp, and S.Steinberg,Fundamentals of
  Grid Generation, (CRC Press, Boca Raton, 1994).
• 4 J. F. Thompson, B. K. Soni, and N. P.
  Weatherill, Handbook of Grid Generation, (CRC
  Press, Boca Raton,1999).
• 5 D. Schurig, et al. Metamaterial
  electromagnetic cloak at microwave frequencies,
  Science 314, 977-980 (2006).

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Reference

• 6 J. Li, and J. B. Pendry, Hiding under the
  carpet A new strategy for cloaking, Phys. Rev.
  Lett. 101, 203901 (2008).
• 7 R. Liu, C. Ji, J. J. Mock, J. Y. Chin, T. J.
  Cui, and D. R. Smith, Broadband ground-plane
  cloak, Science 323, 366-369 (2009).
• 8 J. Valentine, J. Li, T. Zentgraf, G. Bartal,
  and X. Zhang, An optical cloak made of
  dielectrics, Nat. Mater. 8,568-571 (2009).
• 9 L. H. Gabrielli, J. Cardenas, C. B. Poitras,
  and M. Lipson, Silicon nanostructure cloak
  operating at optical frequencies, Nat. Photon.,
  in press (2009).
• 10 H.F. Ma, W.X. Jiang, X.M. Yang, X.Y. Zhou,
  and T. J. CuiCaopact-size and Broadband Carpet
  Cloak and Free-space Cloak,2009.